Curable Silicone Composition, Cured Product Therefrom, And Optical Semiconductor Device

ABSTRACT

A curable silicone composition comprising: (A) an organopolysiloxane represented by the average unit formula: (R 1   3 SiO 1/2 ) a (R 2   2 SiO 2/2 ) b (R 3 SiO 3/2 ) c  (R 1  are alkyl groups, alkenyl groups, aryl groups, or aralkyl groups; R 2  are alkyl groups or alkenyl groups; R 3  is an alkyl group, aryl group, or an aralkyl group, provided that, in a molecule, at least 0.5 mol % of R 1  to R 3  are the alkenyl groups, at least one of R 3  is the aryl group or the aralkyl group; and a, b, and c are numbers satisfying: 0.01≦a≦0.5, 0.4≦b≦0.8, 0.01≦c≦0.5, and a+b+c=1); (B) an organopolysiloxane that is different from component (A); (C) an organopolysiloxane having at least two silicon atom-bonded hydrogen atoms in a molecule; and (D) a hydrosilylation reaction catalyst. A cured product exhibiting excellent dispersibility of phosphor and having high strength and gas barrier properties is formed.

TECHNICAL FIELD

The present invention relates to a curable silicone composition, a curedproduct thereof, and an optical semiconductor device produced using thecomposition.

BACKGROUND ART

Curable silicone compositions are used as sealing agents, protectiveagents, coating agents, or the like for optical semiconductor elementsin optical semiconductor devices such as light emitting diodes (LEDs).Examples of such curable silicone compositions include curable siliconecompositions comprising: a straight-chain organopolysiloxane having atleast two alkenyl groups and at least one aryl group in a molecule; abranched-chain organopolysiloxane having an alkenyl group and an arylgroup; an organopolysiloxane having at least two silicon atom-bondedhydrogen atom in a molecule; and a hydrosilylation reaction catalyst(see Patent Documents 1 to 3).

In general, such a curable silicone composition is used by blending aphosphor to convert the emission wavelength from the LED; however,because of poor dispersibility of the phosphor, the phosphor aggregates,thereby causing a problem in that the light from the LED becomes uneven.

Meanwhile examples of curable silicone compositions that form curedproducts having suitable hardness and strength include a curablesilicone composition comprising: a straight-chain organopolysiloxanehaving at least two alkenyl groups in a molecule; at least two types ofbranched-chain organopolysiloxanes having a mass average molecularweight that is different from one another and comprising SiO_(4/2)units, R₂R′SiO_(1/2) units, and R₃SiO_(1/2) units (in the formula, Rrepresents a monovalent hydrocarbon group having no aliphaticunsaturated bond, and R′ represents an alkenyl group); anorganopolysiloxane having at least two silicon atom-bonded hydrogenatoms in a molecule; and a hydrosilylation reaction catalyst (see PatentDocument 4).

However, the cured product of this composition has high gaspermeability, and when this composition is used as a sealing agent foran optical semiconductor element, electrodes and phosphor thereof arecorroded due to its low barrier properties to sulfur and water. As aresult, there is a problem in that the light extraction efficiency fromLED is reduced.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: Japanese Unexamined Patent Application    Publication No. 2004-143361A-   Patent Document 2: Japanese Unexamined Patent Application    Publication No. 2005-105217A-   Patent Document 3: Japanese Unexamined Patent Application    Publication No. 2008-001828A-   Patent Document 4: Japanese Unexamined Patent Application    Publication No. 2007-131694A

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a curable siliconecomposition that has excellent dispersibility of phosphor and that formsa cured product having high strength and gas barrier properties when thecurable silicone composition is cured. Another object of the presentinvention is to provide a cured product having excellent dispersibilityof phosphor, and high strength and gas barrier properties. Yet anotherobject of the present invention is to provide an optical semiconductordevice with excellent reliability.

Solution to Problem

The curable silicone composition of the present invention ischaracterized by comprising:

-   (A) an organopolysiloxane represented by the average unit formula:

(R¹ ₃SiO_(1/2))_(a)(R² ₂SiO_(2/2))_(b)(R³SiO_(3/2))_(c)

-   -   in the formula, R¹ are the same or different, and alkyl groups        having from 1 to 12 carbons, alkenyl groups having from 2 to 12        carbons, aryl groups having from 6 to 20 carbons, or aralkyl        groups having from 7 to 20 carbons; R² are the same or        different, and alkyl groups having from 1 to 12 carbons or        alkenyl groups having from 2 to 12 carbons; R³ is an alkyl group        having from 1 to 12 carbons, aryl group having from 6 to 20        carbons, or an aralkyl group having from 7 to 20 carbons,        provided that, in a molecule, at least 0.5 mol % of a total        content of the groups represented by R¹, R², and R³ are the        alkenyl groups, at least one of the group represented by R³ is        the aryl group or the aralkyl group; and a, b and c are numbers        satisfying: 0.01≦a≦0.5, 0.4≦b≦0.8, 0.01≦c≦0.5, and a+b+c=1;

-   (B) from 20 to 1,000 parts by mass, relative to 100 parts by mass of    component (A), of an organopolysiloxane represented by the average    unit formula:

(R⁴ ₃SiO_(1/2))_(d)(R⁴ ₂SiO_(2/2))_(e)(R⁴SiO_(3/2))_(f)(SiO_(4/2))_(g)

-   -   in the formula, R⁴ are, the same or different, and alkyl groups        having from 1 to 12 carbons, alkenyl groups having from 2 to 12        carbons, aryl groups having from 6 to 20 carbons, or aralkyl        groups having from 7 to 20 carbons, provided that, in a        molecule, at least 0.5 mol % of a total content of the groups        represented by R⁴ are the alkenyl groups; and d, e, f, and g are        numbers satisfying: 0.01≦d≦0.5, 0≦e≦0.9, 0≦f≦0.9, 0≦g≦0.9, and        d+e+f+g=1; however, if f is a number satisfying: 0≦f≦0.5, g is a        number satisfying: 0<g≦0.9;

-   (C) an organopolysiloxane having at least two silicon atom-bonded    hydrogen atoms in a molecule, in an amount such that a content of    the silicon atom-bonded hydrogen atoms contained in this component    is from 0.1 to 10 mol relative to 1 mol of the total content of the    alkenyl groups contained in components (A) and (B); and

-   (D) a hydrosilylation reaction catalyst, in an amount that    accelerates curing of the composition.

The cured product of the present invention is characterized by curingthe composition described above.

The optical semiconductor device of the present invention ischaracterized by having an optical semiconductor element sealed orcoated with a cured product of the composition described above.

Advantageous Effects of Invention

The curable silicone composition of the present invention forms a curedproduct exhibiting excellent dispersibility of phosphor and having highstrength and gas barrier properties. Furthermore, the cured product ofthe present invention exhibits excellent dispersibility of phosphor andhas high strength and gas barrier properties. Furthermore, the opticalsemiconductor device of the present invention has excellent reliability.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross-sectional view of a surface mounted type LED that isan example of an optical semiconductor device of the present invention.

DESCRIPTION OF EMBODIMENTS

First, the curable silicone composition of the present invention will bedescribed in detail.

Component (A) is an organopolysiloxane represented by the average unitformula:

(R¹ ₃SiO_(1/2))_(a)(R² ₂SiO_(2/2))_(b)(R³SiO_(3/2))_(c).

In the formula, R¹ are the same or different, and alkyl groups havingfrom 1 to 12 carbons, alkenyl groups having from 2 to 12 carbons, arylgroups having from 6 to 20 carbons, or aralkyl groups having from 7 to20 carbons. Specific examples thereof include alkyl groups, such as amethyl group, ethyl group, propyl group, butyl group, pentyl group,hexyl group, heptyl group, octyl group, nonyl group, decyl group,undecyl group, and a dodecyl group; alkenyl groups, such as a vinylgroup, allyl group, butenyl group, pentenyl group, hexenyl group,heptenyl group, octenyl group, nonenyl group, decenyl group, undecenylgroup, and a dodecenyl group; aryl groups, such as a phenyl group, tolylgroup, xylyl group, naphthyl group, anthracenyl group, phenanthrylgroup, and a pyrenyl group; aralkyl groups, such as a benzyl group,phenethyl group, naphthylethyl group, naphthylpropyl group,anthracenylethyl group, phenanthrylethyl group, and a pyrenylethylgroup; and groups in which some or all of the hydrogen atoms bonded inthese groups are substituted with halogen atoms, such as a chlorine atomand bromine atom.

Furthermore, in the formula, R² are the same or different, and alkylgroups having from 1 to 12 carbons or alkenyl groups having from 2 to 12carbons. Specific examples thereof include alkyl groups, such as amethyl group, ethyl group, propyl group, butyl group, pentyl group,hexyl group, heptyl group, octyl group, nonyl group, decyl group,undecyl group, and a dodecyl group; alkenyl groups, such as a vinylgroup, allyl group, butenyl group, pentenyl group, hexenyl group,heptenyl group, octenyl group, nonenyl group, decenyl group, undecenylgroup, and a dodecenyl group; and groups in which some or all of thehydrogen atoms bonded in these groups are substituted with halogenatoms, such as a chlorine atom and a bromine atom. All of R² arepreferably the alkyl groups.

Furthermore, in the formula, R³ is an alkyl group having from 1 to 12carbons, aryl group having from 6 to 20 carbons, or an aralkyl grouphaving from 7 to 20 carbons. Specific examples thereof include alkylgroups, such as a methyl group, ethyl group, propyl group, butyl group,pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decylgroup, undecyl group, and a dodecyl group; aryl groups, such as a phenylgroup, tolyl group, xylyl group, naphthyl group, anthracenyl group,phenanthryl group, and a pyrenyl group; aralkyl groups, such as a benzylgroup, phenethyl group, naphthylethyl group, naphthylpropyl group,anthracenylethyl group, phenanthrylethyl group, and a pyrenylethylgroup; and groups in which some or all of the hydrogen atoms bonded inthese groups are substituted with halogen atoms, such as a chlorine atomand a bromine atom.

In a molecule, at least 0.5 mol % of the total content of the groupsrepresented by R¹, R², and R³, i.e., all of the silicon atom-bondedorganic groups, are the alkenyl groups, and preferably vinyl groups.Furthermore, in a molecule, at least one of the groups represented by R³is the aryl group or the aralkyl group, and preferably a phenyl group.

Furthermore, in the formula, a, b, and c are numbers satisfying:0.01≦a≦0.5, 0.4≦b≦0.8, 0.01≦c≦0.5, and a+b+c=1, and preferably0.01≦a≦0.4, 0.45≦b≦0.8, 0.05≦c≦0.5, and a+b+c=1, or 0.01≦a≦0.3,0.45≦b≦0.75, 0.1≦c≦0.5, and a+b+c=1. This is because, when a is not lessthan the lower limit of the range described above, stickiness is lesslikely to occur on the cured product, and on the other hand, when a isnot greater than the upper limit of the range described above, excellentstrength of the cured product is achieved. Furthermore, when b is notless than the lower limit of the range described above, excellentaffinity of the cured product to a phosphor is achieved, and on theother hand, when b is not greater than the upper limit of the rangedescribed above, mechanical characteristics of the cured product areenhanced. Furthermore, when c is not less than the lower limit of therange described above, excellent refractive index of the cured productis achieved and thus excellent gas barrier properties are achieved, andon the other hand, when c is not greater than the upper limit of therange described above, mechanical characteristics of the cured productare enhanced.

The method of preparing the organopolysiloxane for component (A) is notparticularly limited, and examples thereof include a method ofsubjecting a silane (I) represented by the general formula:

R³SiX₃

a silane (II-1) represented by the general formula:

R² ₂SiX₂

and a disiloxane (III-1) represented by the general formula:

R¹ ₃SiOSiR¹ ₃

to hydrolysis/condensation reaction in the presence of an acid oralkali. The silane (I) is a raw material for introducing siloxane unitsrepresented by formula: R³SiO_(3/2) to the resulting organopolysiloxane.In the formula, R³ is an alkyl group having from 1 to 12 carbons, arylgroup having from 6 to 20 carbons, or an aralkyl group having from 7 to20 carbons, and examples thereof are the same as the groups describedabove. Furthermore, in the formula, X is an alkoxy group, acyloxy group,halogen atom, or a hydroxyl group. Specific examples thereof includealkoxy groups, such as a methoxy group, ethoxy group, and propoxy group;acyloxy groups, such as an acetoxy group; and halogen atoms, such as achlorine atom and a bromine atom.

Examples of the silane (I) include alkoxy silanes, such as phenyltrimethoxysilane, naphthyl trimethoxysilane, anthracenyltrimethoxysilane, phenanthryl trimethoxysilane, pyrenyltrimethoxysilane, phenyl triethoxysilane, naphthyl triethoxysilane,anthracenyl triethoxysilane, phenanthryl triethoxysilane, pyrenyltriethoxysilane, methyl trimethoxysilane, ethyl trimethoxysilane, andmethyl triethoxysilane; acyloxysilanes, such as phenyl triacetoxysilane,naphthyl triacetoxysilane, anthracenyl triacetoxysilane, phenanthryltriacetoxysilane, pyrenyl triacetoxysilane, methyl triacetoxysilane, andethyl triacetoxysilane; halosilanes, such as phenyl trichlorosilane,naphthyl trichlorosilane, anthracenyl trichlorosilane, phenanthryltrichlorosilane, pyrenyl trichlorosilane, methyl trichlorosilane, andethyl trichlorosilane; and hydroxysilanes, such as phenyltrihydroxysilane, naphthyl trihydroxysilane, anthracenyltrihydroxysilane, phenanthryl trihydroxysilane, pyrenyltrihydroxysilane, methyl trihydroxysilane, and ethyl trihydroxysilane.

The silane (II-1) is a raw material for introducing siloxane unitsrepresented by formula: R² ₂SiO_(2/2) to the resultingorganopolysiloxane. In the formula, R² are the same or different, andalkyl groups having from 1 to 12 carbons or alkenyl groups having from 2to 12 carbons, and examples thereof are the same as the groups describedabove. Furthermore, in the formula, X is an alkoxy group, acyloxy group,halogen atom, or a hydroxyl group; and examples thereof are the same asthe groups described above.

Examples of the silane (II-1) include dialkoxysilanes, such asdimethyldimethoxysilane, diethyldimethoxysilane,dipropyldimethoxysilane, methylethyldimethoxysilane,methylvinyldimethoxysilane, dimethyldiethoxysilane,diethyldiethoxysilane, dipropyldiethoxysilane,methylethyldiethoxysilane, and methylvinyldiethoxysilane;diacyloxysilanes, such as dimethyldiacetoxysilane,methylethyldiacetoxysilane, and methylvinyldiacetoxysilane;dihalosilanes, such as dimethyldichlorosilane, diethyldichlorosilane,dipropyldichlorosilane, methylethyldichlorosilane, andmethylvinyldichlorosilane; and dihydroxysilanes, such asdimethyldihydroxysilane, diethyldihydroxysilane,dipropyldihydroxysilane, methylethyldihydroxysilane, andmethylvinyldihydroxysilane.

Furthermore, the disiloxane (III-1) is a raw material for introducingsiloxane units represented by formula: R¹ ₃SiO_(1/2) to the resultingorganopolysiloxane. In the formula, R¹ are the same or different, andalkyl groups having from 1 to 12 carbons, alkenyl groups having from 2to 12 carbons, aryl groups having from 6 to 20 carbons, or aralkylgroups having from 7 to 20 carbons, and examples thereof are the same asthe groups described above.

Examples of the disiloxane (III-1) include1,1,1,3,3,3-hexamethyldisiloxane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane,1,3-divinyl-1,1,3,3-tetraethyldisiloxane,1,1,3,3-tetravinyl-1,3-dimethyldisiloxane,1,1,1,3,3,3-hexavinyldisiloxane,1,3-diphenyl-1,3-divinyl-1,3-dimethyldisiloxane, and1,1,3,3-tetraphenyl-1,3-divinyldisiloxane.

In the method described above, in place of the silane (II-1) or inaddition to the silane (II-1), a cyclic siloxane (II-2) represented bythe general formula:

(R² ₂SiO)_(p)

may be used. In the formula, R² are the same or different, and alkylgroups having from 1 to 12 carbons or alkenyl groups having from 2 to 12carbons, and examples thereof are the same as the groups describedabove. Furthermore, in the formula, p is an integer of 3 or greater.

Examples of the cyclic siloxane (II-2) include1,1,3,3,5,5,7,7-octamethylcyclotetrasiloxane,1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, and1,1,3,3,5,5,7,7-octaethylcyclotetrasiloxane.

Furthermore, in the method described above, in place of the silane(II-1) and the cyclic siloxane (II-2) or in addition to the silane(II-1) and/or the cyclic siloxane (II-2), a straight-chain siloxane(II-3) represented by the general formula:

HO(R² ₂SiO)_(q)H

may be used. In the formula, R² are the same or different, and alkylgroups having from 1 to 12 carbons or alkenyl groups having from 2 to 12carbons, and examples thereof are the same as the groups describedabove. Furthermore, in the formula, q is an integer of 2 or greater.

Examples of the straight-chain siloxane (II-3) include dimethylsiloxaneoligomers capped at both molecular terminals with silanol groups,methylvinylsiloxane oligomers capped at both molecular terminals withsilanol groups, diethylsiloxane oligomers capped at both molecularterminals with silanol groups, and dipropylsiloxane oligomers capped atboth molecular terminals with silanol groups.

Furthermore, in the method described above, in place of the disiloxane(III-1) or in addition to the disiloxane (III-1), a silane (III-2)represented by the general formula:

R¹ ₃SiX

may be used. In the formula, R¹ are the same or different, and alkylgroups having from 1 to 12 carbons, alkenyl groups having from 2 to 12carbons, aryl groups having from 6 to 20 carbons, or aralkyl groupshaving from 7 to 20 carbons, and examples thereof are the same as thegroups described above. Furthermore, in the formula, X is an alkoxygroup, acyloxy group, halogen atom, or a hydroxyl group; and examplesthereof are the same as the groups described above.

Examples of the silane (III-2) include alkoxysilanes, such astrimethylmethoxysilane, triethylmethoxysilane,dimethylvinylmethoxysilane, diethylvinylmethoxysilane,dimethylvinylethoxysilane, diethylvinylethoxysilane,divinylmethylmethoxysilane, trivinylmethoxysilane,methylphenylvinylmethoxysilane, methyldiphenylmethoxysilane, anddiphenylvinylmethoxysilane; acyloxysilanes, such astrimethylacetoxysilane, dimethylvinylacetoxysilane,diethylvinylacetoxysilane, divinylmethylacetoxysilane,trivinylacetoxysilane, methylphenylvinylacetoxysilane,methyldiphenylacetoxysilane, and diphenylvinylacetoxysilane;halosilanes, such as trimethylchlorosilane, dimethylvinylchlorosilane,diethylvinylchlorosilane, divinylmethylchlorosilane,trivinylchlorosilane, methylphenylvinylchlorosilane, andmethyldiphenylchlorosilane; and hydroxysilanes, such astrimethylhydroxysilane, dimethylvinylhydroxysilane,diethylvinylhydroxysilane, divinylmethylhydroxysilane,trivinylhydroxysilane, methylphenylvinylhydroxysilane, andmethyldiphenylhydroxysilane.

In the method described above, the silane (I), the silane (II-1), andthe disiloxane (III-1); or the cyclic siloxane (II-2) and/or thestraight-chain siloxane (II-3) in place of or in addition to the silane(II-1); or the silane (III-2) in place of or in addition to thedisiloxane (III-1); are subjected to hydrolysis/condensation reaction inthe presence of an acid or alkali. Note that at least one type of thesilane (I) used in the method described above is a silane having an arylgroup having from 6 to 20 carbons or aralkyl group having from 7 to 20carbons, and at least one type of the silane (II-1), cyclic siloxane(II-2), straight-chain siloxane (II-3), disiloxane (III-1), or silanecompound (III-2) is a substance having an alkenyl group having from 2 to12 carbons.

Furthermore, examples of the acid used in the method described aboveinclude hydrochloric acid, acetic acid, formic acid, nitric acid, oxalicacid, sulfuric acid, phosphoric acid, polyphosphoric acid,polycarboxylic acid, trifluoromethane sulfonic acid, and ion exchangeresins. Furthermore, examples of the alkali used in the method describedabove include inorganic alkalis, such as potassium hydroxide and sodiumhydroxide; and organic base compounds, such as triethylamine,diethylamine, monoethanolamine, diethanolamine, triethanolamine, ammoniawater, tetramethylammonium hydroxide, alkoxysilanes having an aminogroup, and aminopropyltrimethoxysilane.

In the method described above, an organic solvent may be also used.Examples of the organic solvent include ethers, ketones, acetates,aromatic or aliphatic hydrocarbons, and γ-butyrolactone; and mixtures oftwo or more types of these solvents. Preferred organic solvents areexemplified by propylene glycol monomethyl ether, propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether, propyleneglycol monopropyl ether, propylene glycol monobutyl ether, propyleneglycol mono-t-butyl ether, γ-butyrolactone, toluene, and xylene.

In order to accelerate the hydrolysis/condensation reaction in themethod described above, water or a mixed solution of water and analcohol is preferably added. Methanol and ethanol are preferred asexamples of the alcohol. If an organic solvent is used and this reactionis promoted by heating, the reaction is preferably performed at thereflux temperature of the organic solvent.

Component (B) is an organopolysiloxane represented by the average unitformula:

(R⁴ ₃SiO_(1/2))_(d)(R⁴ ₂SiO_(2/2))_(e)(R⁴SiO_(3/2))_(f)(SiO_(4/2))_(g).

In the formula, R⁴ are the same or different, and alkyl groups havingfrom 1 to 12 carbons, alkenyl groups having from 2 to 12 carbons, arylgroups having from 6 to 20 carbons, or aralkyl groups having from 7 to20 carbons. Specific examples thereof include alkyl groups, such as amethyl group, ethyl group, propyl group, butyl group, pentyl group,hexyl group, heptyl group, octyl group, nonyl group, decyl group,undecyl group, and a dodecyl group; alkenyl groups, such as a vinylgroup, allyl group, butenyl group, pentenyl group, hexenyl group,heptenyl group, octenyl group, nonenyl group, decenyl group, undecenylgroup, and a dodecenyl group; aryl groups, such as a phenyl group, tolylgroup, xylyl group, naphthyl group, anthracenyl group, phenanthrylgroup, and a pyrenyl group; aralkyl groups, such as a benzyl group,phenethyl group, naphthylethyl group, naphthylpropyl group,anthracenylethyl group, phenanthrylethyl group, and a pyrenylethylgroup; and groups in which some or all of the hydrogen atoms bonded inthese groups are substituted with halogen atoms, such as a chlorine atomand a bromine atom. However, in a molecule, at least 0.5 mol % of thetotal content of the groups represented by R⁴, i.e., all of the siliconatom-bonded organic groups, are the alkenyl groups, and preferably vinylgroups.

Furthermore, in the formula, d, e, f, and g are numbers satisfying:0.01≦d≦0.5, 0≦e≦0.9, 0≦f≦0.9, 0≦g≦0.9, and d+e+f+g=1; however, if f is anumber satisfying: 0≦f≦0.5, g is a number satisfying: 0<g≦0.9.Furthermore, preferably d, e, f, and g are numbers satisfying:0.05≦d≦0.4, 0≦e≦0.8, 0≦f≦0.8, 0≦g≦0.8, and d+e+f+g=1; however, if f is anumber satisfying: 0≦f≦0.5, g is a number satisfying: 0<g≦0.8. This isbecause, when d is not less than the lower limit of the range describedabove, excellent strength of the cured product is achieved, and on theother hand, when d is not greater than the upper limit of the rangedescribed above, excellent viscosity of the composition is achieved.Furthermore, when e is not less than the lower limit of the rangedescribed above, excellent flexibility of the cured product is achieved,and on the other hand, when e is not greater than the upper limit of therange described above, excellent miscibility of the cured product tophosphor is achieved. Furthermore, when f is not less than the lowerlimit of the range described above, mechanical properties of the curedproduct are enhanced, and on the other hand, when f is not greater thanthe upper limit of the range described above, excellent viscosity of thecomposition is achieved. Furthermore, when g is not less than the lowerlimit of the range described above, excellent strength of the curedproduct is achieved, and on the other hand, when g is not greater thanthe upper limit of the range described above, excellent mechanicalproperties of the cured product are achieved.

Examples of the method of preparing component (B) include a method ofsubjecting a silane (IV) represented by the general formula:

R⁴SiX₃

and/or a silane (V) represented by the general formula:

SiX₄

and a disiloxane (VI-1) represented by the general formula:

R⁴ ₃SiOSiR⁴ ₃

to hydrolysis/condensation reaction in the presence of an acid oralkali.

The silane (IV) is a raw material for introducing siloxane unitsrepresented by formula: R⁴SiO_(3/2) to the resulting organopolysiloxane.In the formula, R⁴ is an alkyl group having from 1 to 12 carbons or analkenyl group having from 2 to 12 carbons, and examples thereof are thesame as the groups described above. Furthermore, in the formula, X is analkoxy group, acyloxy group, halogen atom, or a hydroxyl group; andexamples thereof are the same as the groups described above.

Examples of the silane (IV) include alkoxysilanes, such asmethyltrimethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, and allyltrimethoxysilane; acyloxysilanes, such asmethyltriacetoxysilane, ethyltriacetoxysilane, andvinyltriacetoxysilane; halosilanes, such as methyltrichlorosilane,ethyltrichlorosilane, and vinyltrichlorosilane; and hydroxysilanes, suchas methyltrihydroxysilane, ethyltrihydroxysilane, andvinyltrihydroxysilane.

Furthermore, the silane (V) is a raw material for introducing siloxaneunits represented by formula: SiO_(4/2) to the resultingorganopolysiloxane. In the formula, X is an alkoxy group, acyloxy group,halogen atom, or a hydroxyl group, and examples thereof are the same asthe groups described above.

Examples of the silane (V) include alkoxysilanes, such astetramethoxysilane and tetraethoxysilane; acyloxysilanes, such astetraacetoxysilane; halosilanes, such as tetrachlorosilane; andhydroxysilanes, such as tetrahydroxysilane.

Furthermore, the disiloxane (VI-1) is a raw material for introducingsiloxane units represented by formula: R⁴ ₃SiO_(1/2) to the resultingorganopolysiloxane. In the formula, R⁴ are alkyl groups having from 1 to12 carbons or alkenyl groups having from 2 to 12 carbons, and examplesthereof are the same as the groups described above. Furthermore, in theformula, X is an alkoxy group, acyloxy group, halogen atom, or ahydroxyl group; and examples thereof are the same as the groupsdescribed above.

Examples of the disiloxane (VI-1) include1,1,1,3,3,3-hexamethyldisiloxane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane, and1,1,3,3-tetravinyl-1,3-dimethyldisiloxane.

In the method described above, in place of the disiloxane (VI-1) or inaddition to the disiloxane (VI-1), a silane (VI-2) represented bygeneral formula:

R⁴ ₃SiX

may be used. In the formula, R⁴ are alkyl groups having from 1 to 12carbons or alkenyl groups having from 2 to 12 carbons, and examplesthereof are the same as the groups described above. Moreover, in theformula, X is an alkoxy group, an acyloxy group, a halogen atom, or ahydroxyl group; and examples thereof are the same as the groupsdescribed above.

Examples of the silane (VI-2) include alkoxysilanes, such astrimethylmethoxysilane, triethylmethoxysilane,vinyldimethylmethoxysilane, divinylmethylmethoxysilane, andtrimethylethoxysilane; acyloxysilanes, such as trimethylacetoxysilane,triethylacetoxysilane, and vinyldimethylacetoxysilane; halosilanes, suchas trimethylchlorosilane, triethyltrichlorosilane, andvinyldimethylchlorosilane; and hydroxysilanes, such astrimethylhydroxysilane, triethylhydroxysilane, andvinyldimethylhydroxysilane.

To introduce siloxane units represented by R⁴ ₂SiO_(2/2) to theresulting organopolysiloxane in the above described method, the silane(II-1), the cyclic siloxane (II-2), the straight-chain siloxane (II-3),or a mixture of at least two types of these may be reacted. Note that atleast one type of the silane compound (IV), the disiloxane (VI-1), thesilane compound (VI-2), the silane compound (II-1), the cyclic siloxanecompound (II-2), and the straight-chain siloxane (II-3) used in themethod described above has an alkenyl group having from 2 to 12 carbons.

Examples of the acid and alkali used in the method described above arethe same as those described above. In the method described above, anorganic solvent may also be used. Examples of the organic solvent arethe same as those described above.

In order to accelerate the hydrolysis/condensation reaction in themethod described above, water or a mixed solution of water and analcohol is preferably added. Methanol and ethanol are preferred examplesof the alcohol. If an organic solvent is used and this reaction ispromoted by heating, the reaction is preferably performed at the refluxtemperature of the organic solvent.

In the present composition, the content of component (B) is in a rangeof 20 to 1,000 parts by mass, preferably 30 to 900 parts by mass or 40to 800 parts by mass, per 100 parts by mass of component (A). This isbecause, when the content of component (B) is not less than the lowerlimit of the range described above, mechanical properties of the curedproduct are enhanced, and on the other hand, when the content ofcomponent (B) is not greater than the upper limit of the range describedabove, excellent viscosity of the composition is achieved.

Component (C) is an organopolysiloxane having at least two siliconatom-bonded hydrogen atoms in a molecule. Examples of the molecularstructure of component (C) include straight chain, partially branchedstraight chain, branched chain, cyclic, and dendritic structures. Ofthese, straight chain, partially branched straight chain, and dendriticstructures are preferable. The bonding positions of the siliconatom-bonded hydrogen atoms in component (C) are not particularlylimited, and examples thereof include a molecular terminal(s) and/orside chain(s) of the molecule. Furthermore, examples of groups bondingto silicon atoms, excluding hydrogen atom, in component (C) includealkyl groups, such as a methyl group, ethyl group, propyl group, butylgroup, pentyl group, hexyl group, heptyl group, octyl group, nonylgroup, decyl group, undecyl group, and a dodecyl group; aralkyl groups,such as a benzyl group, phenethyl group, naphthylethyl group,naphthylpropyl group, anthracenylethyl group, phenanthrylethyl group,and a pyrenylethyl group; halogenated alkyl groups, such as achloromethyl group, 3-chloropropyl group, and 3,3,3-trifluoropropylgroup; glycidoxyalkyl groups, such as 3-glycidoxypropyl group and4-glycidoxybutyl group; and epoxycyclohexylalkyl groups, such as2-(3,4-epoxycyclohexyl)ethyl group and 3-(3,4-epoxycyclohexyl)propylgroup. The viscosity at 25° C. of component (C) is not particularlylimited; however, the viscosity is preferably in a range of 1 to 10,000mPa·s or in a range of 1 to 1,000 mPa·s.

Examples of component (C) include 1,1,3,3-tetramethyldisiloxane,1,3,5,7-tetramethylcyclotetrasiloxane,tris(dimethylhydrogensiloxy)methylsilane,tris(dimethylhydrogensiloxy)phenylsilane,1-(3-glycidoxypropyl)-1,3,5,7-tetramethylcyclotetrasiloxane,1,5-di(3-glycidoxypropyl)-1,3,5,7-tetramethylcyclotetrasiloxane,1-(3-glycidoxypropyl)-5-trimethoxysilylethyl-1,3,5,7-tetramethylcyclotetrasiloxane,methylhydrogenpolysiloxane capped at both molecular terminals withtrimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxanecopolymers capped at both molecular terminals with trimethylsiloxygroups, dimethylpolysiloxane capped at both molecular terminals withdimethylhydrogensiloxy groups, diphenylpolysiloxane capped at bothmolecular terminals with dimethylhydrogensiloxy groups,dimethylsiloxane-methylhydrogensiloxane copolymers capped at bothmolecular terminals with dimethylhydrogensiloxy groups,methylhydrogensiloxane-diphenylsiloxane copolymers capped at bothmolecular terminals with trimethylsiloxy groups,methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymerscapped at both molecular terminals with trimethylsiloxy groups,hydrolysis condensates of trimethoxysilane, copolymers consisting of(CH₃)₂HSiO_(1/2) units and SiO_(4/2) units, copolymers consisting of(CH₃)₂HSiO_(1/2) units, SiO_(4/2) units, and (C₆H₅)SiO_(3/2) units, anda mixture of at least two types of these.

Furthermore, examples of component (C) include the followingorganosiloxanes. Note that, in the formulae, Me, Vi, Ph, and Naphrepresent a methyl group, vinyl group, phenyl group, and a naphthylgroup, respectively; m and m′ are each independently an integer of 1 orgreater; and h, i, j, and k are numbers satisfying: 0<h<1, 0<i<1, 0<j<1,0<k<1, and h+i+j+k=1.

HMe₂SiO(Ph₂SiO)_(m)SiMe₂H

HMePhSiO(Ph₂SiO)_(m)SiMePhH

HMeNaphSiO(Ph₂SiO)_(m)SiMeNaphH

HMePhSiO(Ph₂SiO)_(m)(MePhSiO)_(m′)SiMePhH

HMePhSiO(Ph₂SiO)_(m)(Me₂SiO)_(m′)SiMePhH

(HMe₂SiO_(1/2))_(h)(PhSiO_(3/2))_(i)

(HMePhSiO_(1/2))_(h)(PhSiO_(3/2))_(i)

(HMePhSiO_(1/2))_(h)(NaphSiO_(3/2))_(i)

(HMe₂SiO_(1/2))_(h)(NaphSiO_(3/2))_(i)

(HMePhSiO_(1/2))_(n)(HMe₂SiO_(1/2))_(i)(PhSiO_(3/2))_(j)

(HMe₂SiO_(1/2))_(h)(SiO_(4/2))_(i)

(HMe₂SiO_(1/2))_(h)(SiO_(4/2))_(i)(PhSiO_(3/2))_(j)

(HMePhSiO_(1/2))_(h)(SiO_(4/2))_(i)(PhSiO_(3/2))_(j)

(HMe₂SiO_(1/2))_(h)(SiO_(4/2))_(i)(NaphSiO_(3/2))_(j)

(HMePhSiO_(1/2))_(h)(SiO_(4/2))_(i)(NaphSiO_(3/2))_(j)

(HMePhSiO_(1/2))_(n)(HMe₂SiO_(1/2))_(i)(NaphSiO_(3/2))_(j)

(HMePhSiO_(1/2))_(n)(HMe₂SiO_(1/2))_(i)(SiO_(4/2))_(i)(NaphSiO_(3/2))_(k)

(HMePhSiO_(1/2))_(n)(HMe₂SiO_(1/2))_(i)(SiO_(4/2))_(j)(PhSiO_(3/2))_(k)

The content of component (C) in the present composition is an amountsuch that the silicon atom-bonded hydrogen atoms contained in component(C) is in a range of 0.1 to 10 mol, and preferably in a range of 0.5 to5 mol, per 1 mol of total alkenyl groups contained in components (A) and(B). This is because, when the content of component (C) is not less thanthe lower limit of the range described above, the resulting compositionis cured sufficiently, and on the other hand, when the content is notgreater than the upper limit of the range described above, heatresistance of the resulting cured product is enhanced, and reliabilityof an optical semiconductor device produced using this composition isthus enhanced.

Component (D) is a hydrosilylation reaction catalyst used to acceleratecuring of the present composition. Examples of component (D) includeplatinum-based catalysts, rhodium-based catalysts, and palladium-basedcatalysts. The platinum-based catalyst is preferable. Examples of theplatinum-based catalyst include platinum-based compounds, such asplatinum fine powder, platinum black, platinum-supporting silica finepowder, platinum-supporting activated carbon, chloroplatinic acid,alcohol solutions of chloroplatinic acid, olefin complexes of platinum,and alkenylsiloxane complexes of platinum.

The content of component (D) in the present composition is an amountthat accelerates curing the present composition. Specifically, thecontent of component (D) in the present composition is an amount suchthat the amount of the metal atoms in this catalyst is in a range of0.01 to 1,000 ppm by mass. This is because, when the content ofcomponent (D) is not less than the lower limit of the range describedabove, the resulting composition is cured sufficiently, and on the otherhand, when the content of component (D) is not greater than the upperlimit of the range described above, the resulting cured product isresistant to discoloration.

The present composition may contain (E) a hydrosilylation reactioninhibitor in order to prolong the usable time at ambient temperature andto enhance storage stability. Examples of component (E) include alkynealcohols, such as 1-ethynylcyclohexan-1-ol, 2-methyl-3-butyn-2-ol,3,5-dimethyl-1-hexyn-3-ol, and 2-phenyl-3-butyn-2-ol; enyne compounds,such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne;methylalkenylsiloxane oligomers, such as1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane;alkynoxysilanes, such as dimethyl bis-(3-methyl-1-butyn-3-oxy)silane andmethylvinyl bis-(3-methyl-1-butyn-3-oxy)silane; andtriallylisocyanurate-based compounds.

The content of component (E) is not particularly limited; however, thecontent is preferably in a range of 0.01 to 3 parts by mass or in arange of 0.01 to 1 part by mass, per 100 parts by mass of the totalamount of components (A) to (C). This is because, when the content ofcomponent (E) is not less than the lower limit of the range describedabove, suitable usable life of the present composition is ensured, andon the other hand, when the content is not greater than the upper limitof the range described above, suitable workability of the presentcomposition is ensured.

Furthermore, the present composition may contain (F) an adhesionpromoter in order to further enhance adhesion to a substrate with whichthe composition makes contact during curing. Component (F) is preferablyan organosilicon compound having at least one alkoxy group bonded to asilicon atom in a molecule. Examples of the alkoxy group include amethoxy group, ethoxy group, propoxy group, butoxy group, and amethoxyethoxy group. The methoxy group and ethoxy group are preferable.Furthermore, examples of other group(s), excluding alkoxy group, thatbond to a silicon atom of the organosilicon compound include alkylgroups, such as a methyl group, ethyl group, propyl group, butyl group,pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decylgroup, undecyl group, and a dodecyl group; alkenyl groups, such as avinyl group, allyl group, butenyl group, pentenyl group, hexenyl group,heptenyl group, octenyl group, nonenyl group, decenyl group, undecenylgroup, and a dodecenyl group; aryl groups, such as a phenyl group, tolylgroup, xylyl group, naphthyl group, anthracenyl group, phenanthrylgroup, and a pyrenyl group; aralkyl groups, such as a benzyl group,phenethyl group, naphthylethyl group, naphthylpropyl group,anthracenylethyl group, phenanthrylethyl group, and a pyrenylethylgroup; groups in which some or all of the hydrogen atoms bonded in thesegroups are substituted with halogen atoms, such as a chlorine atom and abromine atom; glycidoxyalkyl groups, such as 3-glycidoxypropyl group and4-glycidoxybutyl group; epoxycyclohexylalkyl groups, such as2-(3,4-epoxycyclohexyl)ethyl group and 3-(3,4-epoxycyclohexyl)propylgroup; oxiranylalkyl groups, such as 4-oxiranylbutyl group and8-oxiranyloctyl group; acryloxyalkyl groups, such as3-methacryloxypropyl group; and isocyanate groups, isocyanurate groups,and hydrogen atoms.

The organosilicon compound preferably has a group that can react with analkenyl group or a silicon atom-bonded hydrogen atom in the presentcomposition. Specifically, the organosilicon compound preferably has asilicon atom-bonded hydrogen atom or an alkenyl group. Examples of themolecular structure of the silicon compound include straight chain,partially branched straight chain, branched chain, cyclic, and net-likestructures. Of these, straight chain, branched chain, and net-likestructures are preferable. Examples of such an organosilicon compoundinclude silane compounds, such as 3-glycidoxypropyltrimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-methacryloxypropyltrimethoxysilane; siloxane compounds having at least one ofsilicon atom-bonded alkenyl groups or at least one silicon atom-bondedhydrogen atoms, and at least one silicon atom-bonded alkoxy group in amolecule; mixtures of a silane compound or siloxane compound having atleast one silicon atom-bonded alkoxy group and a siloxane compoundhaving at least one silicon atom-bonded hydroxyl group and at least onesilicon atom-bonded alkenyl group in a molecule; siloxane compoundsrepresented by the average unit formula:

(in the formula, r, s, and t each independently represent a positivenumber); and siloxane compounds represented by the average unit formula:

(in the formula, r, s, t, and u each independently represent a positivenumber).

The content of component (F) is not particularly limited; however, thecontent is preferably in a range of 0.1 to 5 parts by mass or in a rangeof 1 to 5 parts by mass, per 100 parts by mass of the total amount ofcomponents (A) to (C). This is because, when the content of component(F) is not less than the lower limit of the range described above,excellent adhesion is achieved, and on the other hand, when the contentis not greater than the upper limit of the range described above,excellent storage stability is achieved.

Furthermore, the present composition may contain (G) a phosphor in orderto convert the emission wavelength from an optical semiconductorelement. Examples of component (G) include substances widely used inlight emitting diodes (LEDs), such as yellow, red, green, and bluelight-emitting phosphors, such as oxide-based phosphors,oxynitride-based phosphors, nitride-based phosphors, sulfide-basedphosphors, and oxysulfide-based phosphors. Examples of oxide-basedphosphors include yttrium, aluminum, and garnet-type YAG green to yellowlight-emitting phosphors containing cerium ions; terbium, aluminum, andgarnet-type TAG yellow light-emitting phosphors containing cerium ions;and silicate green to yellow light-emitting phosphors containing ceriumor europium ions. Examples of oxynitride-based phosphors includesilicon, aluminum, oxygen, and nitrogen-type SiAlON red to greenlight-emitting phosphors containing europium ions. Examples ofnitride-based phosphors include calcium, strontium, aluminum, silicon,and nitrogen-type CASN red light-emitting phosphors containing europiumions. Examples of sulfide-based phosphors include ZnS greenlight-emitting phosphors containing copper ions or aluminum ions.Examples of oxysulfide-based phosphors include Y₂O₂S red light-emittingphosphors containing europium ions. Two or more types of these phosphorsmay be combined for use.

The average particle diameter of component (G) is not particularlylimited; however, the average particle diameter is preferably in a rangeof 1 to 50 μm or in a range of 5 to 20 μm. This is because, when theaverage particle diameter of component (G) is not less than the lowerlimit of the range described above, increase in viscosity upon mixing issuppressed, and on the other hand, when the average particle diameter isnot greater than the upper limit of the range described above, excellentlight transmittance is achieved.

The content of component (G) is in a range of 0.1 to 70% by mass, andpreferably in a range of 1 to 70% by mass or in a range of 5 to 70% bymass, relative to the total amount of components (A) to (C). This isbecause, when the content of component (G) is not less than the lowerlimit of the range described above, wavelength conversion can beperformed efficiently, and on the other hand, when the content is notgreater than the upper limit of the range described above, handleabilityof the resulting composition is enhanced.

In order to sufficiently suppress the discoloration of silver electrodesor silver plating of a substrate in an optical semiconductor device dueto sulfur-containing gas in the air, the present composition may containat least one type of a fine powder having an average particle diameterof 0.1 nm to 5 μm selected from the group consisting of zinc oxide finepowders surface-coated with at least one type of oxide of an elementselected from the group consisting of Al, Ag, Cu, Fe, Sb, Si, Sn, Ti,Zr, and rare earth elements, zinc oxide fine powders surface-treatedwith organosilicon compounds having no alkenyl groups, and hydrate finepowders of zinc carbonate.

In a zinc oxide fine powder surface-coated with an oxide, examples ofrare earth elements include yttrium, cerium, and europium. Examples ofoxides on the surface of the zinc oxide fine powder include Al₂O₃, AgO,Ag₂O, Ag₂O₃, CuO, Cu₂O, FeO, Fe₂O₃, Fe₃O₄, Sb₂O₃, SiO₂, SnO₂, Ti₂O₃,TiO₂, Ti₃O₅, ZrO₂, Y₂O₃, CeO₂, Eu₂O₃, and mixtures of two or more typesof these oxides.

The content of the powder is not particularly limited; however, thecontent is preferably in a range of 1 ppm to 10% or in a range of 1 ppmto 5%, by mass, of the present composition. This is because, when thecontent of the powder is not less than the lower limit of the rangedescribed above, discoloration of silver electrodes or silver plating ofa substrate in an optical semiconductor device due to asulfur-containing gas is sufficiently suppressed, and on the other hand,when the content is not greater than the upper limit of the rangedescribed above, fluidity of the resulting composition is notdiminished.

Furthermore, the present composition may also contain a triazole-basedcompound to enable further suppression of the discoloration of silverelectrodes or silver plating of a substrate in an optical semiconductordevice due to a sulfur-containing gas in the air. Examples of thetriazole-based compound include 1H-1,2,3-triazole, 2H-1,2,3-triazole,1H-1,2,4-triazole, 4H-1,2,4-triazole,2-(2′-hydroxy-5-methylphenyl)benzotriazole, 1H-1,2,3-triazole,2H-1,2,3-triazole, 1H-1,2,4-triazole, 4H-1,2,4-triazole, benzotriazole,tolyltriazole, carboxybenzotriazole,1H-benzotriazole-5-methylcarboxylate, 3-amino-1,2,4-triazole,4-amino-1,2,4-triazole, 5-amino-1,2,4-triazole,3-mercapto-1,2,4-triazole, chlorobenzotriazole, nitrobenzotriazole,aminobenzotriazole, cyclohexano[1,2-d]triazole,4,5,6,7-tetrahydroxytolyltriazole, 1-hydroxybenzotriazole,ethylbenzotriazole, naphthotriazole, 1-N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]tolyltriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]carboxybenzotriazole, 1-[N,N-bis(2-hydroxyethyl)-aminomethyl]benzotriazole, 1-[N,N-bis(2-hydroxyethyl)-aminomethyl]tolyltriazole, 1-[N,N-bis(2-hydroxyethyl)-aminomethyl]carboxybenzotriazole, 1-[N,N-bis(2-hydroxypropyl)aminomethyl]carboxybenzotriazole,1-[N,N-bis(1-butyl)aminomethyl]carboxybenzotriazole,1-[N,N-bis(1-octyl)aminomethyl]carboxybenzotriazole,1-(2′,3′-di-hydroxypropyl)benzotriazole,1-(2′,3′-di-carboxyethyl)benzotriazole,2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)benzotriazole,2-(2′-hydroxy-3′,5′-aminophenyl)benzotriazole,2-(2′-hydroxy-4′-octoxyphenyl)benzotriazole,2-(2′-hydroxy-5′-tert-butylphenyl)benzotriazole,1-hydroxybenzotriazole-6-carboxylic acid, 1-oleoylbenzotriazole,1,2,4-triazol-3-ol, 5-amino-3-mercapto-1,2,4-triazole,5-amino-1,2,4-triazole-3-carboxylic acid, 1,2,4-triazole-3-carboxyamide,4-aminourazole, and 1,2,4-triazol-5-one. The content of thetriazole-based compound is not particularly limited; however, thecontent is in a range of 0.01 ppm to 3% by mass, and preferably in arange of 0.1 ppm to 1% by mass, of the present composition.

Furthermore, the present composition may contain a straight-chainorganopolysiloxane having at least two silicon atom-bonded alkenylgroups in a molecule. Examples of the alkenyl group include a vinylgroup, allyl group, butenyl group, pentenyl group, hexenyl group,heptenyl group, octenyl group, nonenyl group, decenyl group, undecenylgroup, and a dodecenyl group. Of these, the vinyl group is preferable.Examples of the group bonding to the silicon atom other than alkenylgroups include alkyl groups, such as a methyl group, ethyl group, propylgroup, butyl group, pentyl group, hexyl group, heptyl group, octylgroup, nonyl group, decyl group, undecyl group, and a dodecyl group;aryl groups, such as a phenyl group, tolyl group, xylyl group, naphthylgroup, anthracenyl group, phenanthryl group, and a pyrenyl group;aralkyl groups, such as a benzyl group, phenethyl group, naphthylethylgroup, naphthylpropyl group, anthracenylethyl group, phenanthrylethylgroup, and a pyrenylethyl group; and groups in which some or all of thehydrogen atoms bonded in these groups are substituted with halogenatoms, such as a chlorine atom and a bromine atom. Of these, the methylgroup and phenyl group are preferable. The viscosity at 25° C. of theorganopolysiloxane is not particularly limited; however, the viscosityis preferably in a range of 10 to 10,000,000 mPa·s or in a range of 100to 1,000,000 mPa·s.

The following compounds are examples of such organopolysiloxanes. Notethat, in the formulae, Me, Vi, and Ph represent a methyl group, vinylgroup, and a phenyl group, respectively; and n and n′ are eachindependently an integer of 1 or greater.

ViMe₂SiO(Me₂SiO)_(n)SiMe₂Vi

ViPhMeSiO(Me₂SiO)_(n)SiMePhVi

ViPh₂SiO(Me₂SiO)_(n)SiPh₂Vi

ViMe₂SiO(Me₂SiO)_(n)(Ph₂SiO)_(n′)SiMe₂Vi

ViPhMeSiO(Me₂SiO)_(n)(Ph₂SiO)_(n′)SiPhMeVi

ViPh₂SiO(Me₂SiO)_(n)(Ph₂SiO)_(n′)SiPh₂Vi

ViMe₂SiO(MePhSiO)_(n)SiMe₂Vi

MePhViSiO(MePhSiO)_(n)SiMePhVi

Ph₂ViSiO(MePhSiO)_(n)SiPh₂Vi

ViMe₂SiO(Ph₂SiO)_(n)(PhMeSiO)_(n′)SiMe₂Vi

ViPhMeSiO(Ph₂SiO)_(n)(PhMeSiO)_(n′)SiPhMeVi

ViPh₂SiO(Ph₂SiO)_(n)(PhMeSiO)_(n′)SiPh₂Vi

The content of the organopolysiloxane is not particularly limited;however, the content is preferably in a range of 0 to 50 parts by massor in a range of 0 to 30 parts by mass per 100 parts by mass of thetotal amount of components (A) to (C).

Furthermore, an inorganic filler such as silica, glass, alumina or zincoxide; an organic resin fine powder of a polymethacrylate resin or thelike; a heat-resistant agent, a dye, a pigment, a flame retardant, asolvent, and the like may be contained as optional components in thepresent composition at levels that do not impair the object of thepresent invention.

The viscosity at 25° C. of the present composition is not particularlylimited; however, the viscosity is preferably in a range of 100 to500,000 mPa·s or in a range of 100 to 100,000 mPa·s. The presentcomposition is such that curing occurs either at room temperature orunder heating, but it is preferable to heat the composition in order toachieve rapid curing. The heating temperature is preferably in a rangeof 50 to 200° C.

The cured product of the present invention will now be described indetail.

The cured product of the present invention is formed by curing thecurable silicone composition described above. The shape of the curedproduct is not particularly limited, and examples include a sheet shapeand a film shape. Furthermore, this cured product may be in the form ofsealing or coating an optical semiconductor element or the like.

The optical semiconductor device of the present invention will now beexplained in detail.

The optical semiconductor device of the present invention ischaracterized in that a light emitting element is sealed or coated witha cured product of the curable silicone composition described above.Examples of such an optical semiconductor device of the presentinvention include a light emitting diode (LED), a photocoupler, and aCCD. Examples of optical semiconductor elements include light emittingdiode (LED) chips and solid-state image sensing devices.

FIG. 1 illustrates a cross-sectional view of a single surface mountedtype LED, which is one example of the optical semiconductor device ofthe present invention. In the LED shown in FIG. 1, the opticalsemiconductor element 1 is die bonded to a lead frame 2, and thisoptical semiconductor element 1 is further wire bonded to a lead frame 3by a bonding wire 4. A frame material 5 is provided around this opticalsemiconductor element 1, and the optical semiconductor element 1 insidethe frame material 5 is sealed by a cured product 6 of the curablesilicone composition of the present invention.

An example of the method for producing the surface mounted type LEDillustrated in FIG. 1 is a method comprising die-bonding the opticalsemiconductor element 1 to the lead frame 2, wire-bonding this opticalsemiconductor element 1 and the lead frame 3 by means of a metal bondingwire 4, charging the curable silicone composition of the presentinvention inside the frame material 5 provided around the periphery ofthe optical semiconductor element 1, and then curing the curablesilicone composition by heating at 50 to 200° C.

EXAMPLES

The curable silicone composition, the cured product thereof, and theoptical semiconductor device of the present invention will be describedin detail hereinafter using Examples. Note that values of viscosity inExamples are the values of viscosity at 25° C. In the formulae, Me, Ph,Vi, and Ep represent a methyl group, phenyl group, vinyl group, and3-glycidoxypropyl group, respectively. Furthermore, the characteristicsof the curable silicone composition and the cured product thereof weremeasured as follows, and the results are shown in Table 1.

[Refractive Index of Curable Silicone Composition]

The refractive index at 25° C. of the curable silicone composition wasmeasured by an Abbe refractometer. A 589 nm light source was used forthe measurement.

[Tensile Strength]

A sheet-like cured product having a thickness of 1 mm was prepared bycuring the curable silicone composition at 150° C. for 1 hour using apress. Thereafter, this cured product was punched out in a No. 3dumbbell-shape stipulated in JIS K 6251-1993, “Tensile testing methodsfor vulcanized rubber”, and then the strength (MPa) at break wasmeasured using the Autograph, manufactured by Shimadzu Corporation, andevaluated as follows.

◯: Strength at break was 3 MPa or greater

Δ: Strength at break was 1 MPa or greater but less than 3 MPa

x: Strength at break was less than 1 MPa

[Dispersibility of Phosphor]

To 100 parts by mass of the curable silicone composition, 3 parts bymass of YAG phosphor (MX311(B), manufactured by Intematix Corporation)as component (G) was mixed using a dental mixer. Thereafter, the curablesilicone composition containing the phosphor was coated on a glass plateand heated in an oven at 150° C. for 1 hour to be cured. The conditionof dispersion of the phosphor in the obtained cured product was visuallyobserved and result thereof was evaluated as follows.

◯: Phosphor is uniformly dispersed

Δ: Phospher is partially aggregated

x: Phospher is mostly aggregated

[Oxygen Permeability]

A sheet-like cured product having a thickness of 1 mm was prepared bycuring the curable silicone composition at 150° C. for 1 hour using apress. The oxygen permeability of this cured product was measured at atemperature of 23° C. using the Oxygen permeation analyzer (model:8001), manufactured by Systech Illinois.

◯: Oxygen permeability was less than 10,000 cc/m²·24 h

Δ: Oxygen permeability was 10,000 cc/m²·24 h or greater but less than15,000 cc/m²·24 h

x: Oxygen permeability was 15,000 cc/m²·24 h or greater

Synthesis Example 1

In a 4-necked flask equipped with a stirrer, a reflux condenser, and athermometer, 62.8 g (0.34 mol) of1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 183.2 g (0.62 mol) ofoctamethylcyclotetrasiloxane, 267.2 g (1.35 mol) ofphenyltrimethoxysilane, and 0.29 g of trifluoromethanesulfonic acid wereloaded and, while the mixture was being stirred, 72.8 g (4.04 mol) ofwater was added dropwise over 30 minutes. After completion of theaddition, the mixture was heated to 85° C., and generated methanol wasdistilled off. Azeotropic dehydration was performed after adding 105 gof toluene and 2.8 g of 30% by mass potassium hydroxide aqueoussolution. Thereafter, the mixture was maintained at 125° C. for 6 hours,then cooled to room temperature, and neutralized by 0.9 g of aceticacid. After the generated salt was filtered, low boiling pointsubstances were removed from the obtained transparent solution byheating under reduced pressure to prepare 400 g (yield: 95%) oforganopolysiloxane that was colorless and transparent, that had a numberaverage molecular weight of 2,300, and that was represented by theaverage unit formula:

(ViMe₂SiO_(1/2))_(0.15)(Me₂SiO_(2/2))_(0.55)(PhSiO_(3/2))_(0.30).

Synthesis Example 2

In a 4-necked flask equipped with a stirrer, a reflux condenser, and athermometer, 21.4 g (0.11 mol) of1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 221.0 g (0.74 mol) ofoctamethylcyclotetrasiloxane, 272.7 g (1.38 mol) ofphenyltrimethoxysilane, and 0.29 g of trifluoromethanesulfonic acid wereloaded and, while the mixture was being stirred, 74.3 g (4.13 mol) ofwater was added dropwise over 30 minutes. After completion of theaddition, the mixture was heated to 85° C., and generated methanol wasdistilled off. Azeotropic dehydration was performed after adding 105 gof toluene and 2.8 g of 30% by mass potassium hydroxide aqueoussolution. Thereafter, the mixture was maintained at 125° C. for 6 hours,then cooled to room temperature, and neutralized by 0.9 g of aceticacid. After the generated salt was filtered, low boiling pointsubstances were removed from the obtained transparent solution byheating under reduced pressure to prepare 400 g (yield: 95%) oforganopolysiloxane that was colorless and transparent, that had a numberaverage molecular weight of 2,700, and that was represented by theaverage unit formula:

(ViMe₂SiO_(1/2))_(0.05)(Me₂SiO_(2/2))_(0.65)(PhSiO_(3/2))_(0.30).

Synthesis Example 3

In a 4-necked flask equipped with a stirrer, a reflux condenser, and athermometer, 32.6 g (0.17 mol) of1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 178.4 g (0.60 mol) ofoctamethylcyclotetrasiloxane, 320.8 g (1.62 mol) ofphenyltrimethoxysilane, and 0.31 g of trifluoromethanesulfonic acid wereloaded and, while the mixture was being stirred, 87.4 g (4.85 mol) ofwater was added dropwise over 30 minutes. After completion of theaddition, the mixture was heated to 85° C., and generated methanol wasdistilled off. Azeotropic dehydration was performed after adding 105 gof toluene and 2.8 g of 30% by mass potassium hydroxide aqueoussolution. Thereafter, the mixture was maintained at 125° C. for 6 hours,then cooled to room temperature, and neutralized by 0.9 g of aceticacid. After the generated salt was filtered, low boiling pointsubstances were removed from the obtained transparent solution byheating under reduced pressure to prepare 400 g (yield: 95%) oforganopolysiloxane that was colorless and transparent, that had a numberaverage molecular weight of 3,100, and that was represented by theaverage unit formula:

(ViMe₂SiO_(1/2))_(0.08)(Me₂SiO_(2/2))_(0.55)(PhSiO_(3/2))_(0.37).

Synthesis Example 4

In a 4-necked flask equipped with a stirrer, a reflux condenser, and athermometer, 39.9 g (0.21 mol) of1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 158.8 g (0.54 mol) ofoctamethylcyclotetrasiloxane, 339.7 g (1.71 mol) ofphenyltrimethoxysilane, and 0.32 g of trifluoromethanesulfonic acid wereloaded and, while the mixture was being stirred, 92.6 g (5.24 mol) ofwater was added dropwise over 30 minutes. After completion of theaddition, the mixture was heated to 85° C., and generated methanol wasdistilled off.

Azeotropic dehydration was performed after adding 105 g of toluene and2.8 g of 30% by mass potassium hydroxide aqueous solution. Thereafter,the mixture was maintained at 125° C. for 6 hours, then cooled to roomtemperature, and neutralized by 0.9 g of acetic acid. After thegenerated salt was filtered, low boiling point substances were removedfrom the obtained transparent solution by heating under reduced pressureto prepare 400 g (yield: 95%) of organopolysiloxane that was colorlessand transparent, that had a number average molecular weight of 2,800,and that was represented by the average unit formula:

(ViMe₂SiO_(1/2))_(0.10)(Me₂SiO_(2/2))_(0.50)(PhSiO_(3/2))_(0.40).

Synthesis Example 5

In a reaction vessel, 246.3 g of cyclic diphenylpolysiloxane, 598.4 g ofcyclic dimethylpolysiloxane, 5.78 g of1,3-divinyl-1,1,3,3-dimethyldisiloxane, and 0.26 g of potassiumhydroxide were loaded and heated to 150° C. After the temperaturereached 150° C., the reaction was performed for 7 hours. Thereafter, apredetermined amount of vinyldimethylchlorosilane was added toneutralize, and then low boiling point substances were removed underreduced pressure to prepare a dimethylsiloxane-diphenylsiloxanecopolymer that was colorless and transparent, that had a refractiveindex of 1.46 and a viscosity of 5.8 Pas, and that was represented bythe formula:

ViMe₂SiO(Me₂SiO)₂₆₀(Ph₂SiO)₄₀SiMe₂Vi.

Synthesis Example 6

In a 4-necked flask equipped with a stirrer, a reflux condenser, and athermometer, 54.7 g (0.29 mol) of1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 87.1 g (0.29 mol) ofoctamethylcyclotetrasiloxane, 427.0 g (2.15 mol) ofphenyltrimethoxysilane, and 0.34 g of trifluoromethanesulfonic acid wereloaded and, while the mixture was being stirred, 110.8 g (6.15 mol) ofwater was added dropwise over 30 minutes. After completion of theaddition, the mixture was heated to 85° C., and generated methanol wasdistilled off. Azeotropic dehydration was performed after adding 105 gof toluene and 2.8 g of 30% by mass potassium hydroxide aqueoussolution. Thereafter, the mixture was maintained at 125° C. for 6 hours,then cooled to room temperature, and neutralized by 0.9 g of aceticacid. After the generated salt was filtered, low boiling pointsubstances were removed from the obtained transparent solution byheating under reduced pressure to prepare 400 g (yield: 95%) oforganopolysiloxane that was colorless and transparent, that had a numberaverage molecular weight of 1,800, and that was represented by theaverage unit formula:

(ViMe₂SiO_(1/2))_(0.15)(Me₂SiO_(2/2))_(0.30)(PhSiO_(3/2))_(0.55).

Synthesis Example 7

In a 4-necked flask equipped with a stirrer, a reflux condenser, and athermometer, 82.2 g (0.44 mol) of1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 143 g of water, 0.38 g oftrifluoromethanesulfonic acid, and 500 g of toluene were loaded and,while the mixture was being stirred, 524.7 g (2.65 mol) ofphenyltrimethoxysilane was added dropwise over 1 hour. After completionof the addition, the mixture was heat-refluxed for 1 hour. The mixturewas then cooled, and after the bottom layer was separated, the toluenesolution layer was washed with water three times. To the water-washedtoluene solution layer, 314 g (1.42 mol) of 3-glycidoxypropylmethyldimethoxysilane, 130 g of water, and 0.50 g of potassium hydroxidewere added, and the mixture was heat-refluxed for 1 hour. Methanol wasthen distilled off, and the excess water was removed by azeotropicdehydration. After heat-refluxing for 4 hours, the toluene solution wascooled, neutralized with 0.55 g of acetic acid, and washed with waterthree times. After the water was removed, toluene was distilled offunder reduced pressure to prepare an adhesion-imparting agent that had aviscosity of 8,500 mPa·s and that was represented by the average unitformula:

(ViMe₂SiO_(1/2))_(0.18)(PhSiO_(3/2))_(0.53)(EpMeSiO_(2/2))_(0.29).

Practical Examples 1 to 7 and Comparative Examples 1 to 3

The following components were mixed in the compositions (part by mass)shown in Table 1 to prepare curable silicone compositions. Note that the“SiH/Vi” values in the Table 1 refer to the number of moles of siliconatom-bonded hydrogen atoms contained in components corresponding tocomponent (C), relative to 1 mole of vinyl groups contained incomponents corresponding to components (A) and (B). Furthermore, thecontent of component (D) is expressed in terms of the content (ppm bymass) of platinum metal relative to the content of the curable siliconecomposition.

The following components were used as component (A).

Component (A-1): an organopolysiloxane prepared in Synthesis Example 1and represented by the average unit formula:

(ViMe₂SiO_(1/2))_(0.15)(Me₂SiO_(2/2))_(0.55)(PhSiO_(3/2))_(0.30).

(content of vinyl groups relative to content of all of the siliconatom-bonded organic groups: 8.1 mol %)Component (A-2): an organopolysiloxane prepared in Synthesis Example 2and represented by the average unit formula:

(ViMe₂SiO_(1/2))_(0.05)(Me₂SiO_(2/2))_(0.65)(PhSiO_(3/2))_(0.30).

(content of vinyl groups relative to content of all of the siliconatom-bonded organic groups: 2.9 mol %)Component (A-3): an organopolysiloxane prepared in Synthesis Example 3and represented by the average unit formula:

(ViMe₂SiO_(1/2))_(0.05)(Me₂SiO_(2/2))_(0.55)(PhSiO_(3/2))_(0.37).

(content of vinyl groups relative to content of all of the siliconatom-bonded organic groups: 4.7 mol %)Component (A-4): an organopolysiloxane prepared in Synthesis Example 4and represented by the average unit formula:

(ViMe₂SiO_(1/2))_(0.10)(Me₂SiO_(2/2))_(0.50)(PhSiO_(3/2))_(0.40).

(content of vinyl groups relative to content of all of the siliconatom-bonded organic groups: 5.9 mol %)Component (A-5): a phenylmethylpolysiloxane capped at both molecularterminals with dimethylvinylsiloxy groups that had a viscosity of 2,000mPa·sComponent (A-6): an organopolysiloxane prepared in Synthesis Example 5and represented by the average unit formula:

ViMe₂SiO(Me₂SiO)₂₆₀(Ph₂SiO)₄₀SiMe₂Vi.

The following components were used as component (B).

Component (B-1): an organopolysiloxane represented by the average unitformula:

(ViMe₂SiO_(1/2))_(0.25)(PhSiO_(3/2))_(0.75)

(content of vinyl groups relative to content of all of the siliconatom-bonded organic groups: 16.7 mol %)Component (B-2): an organopolysiloxane prepared in Synthesis Example 6and represented by the average unit formula:

(ViMe₂SiO_(1/2))_(0.15)(Me₂SiO_(2/2))_(0.30)(PhSiO_(3/2))_(0.55)

(content of vinyl groups relative to content of all of the siliconatom-bonded organic groups: 9.4 mol %)Component (B-3): an organopolysiloxane represented by the average unitformula:

(ViMe₂SiO_(1/2))_(0.10)(Me₃SiO_(1/2))_(0.40)(SiO_(4/2))_(0.50)

(content of vinyl groups relative to content of all of the siliconatom-bonded organic groups: 6.7 mol %)Component (B-4): an organopolysiloxane represented by the average unitformula:

(ViMe₂SiO_(1/2))_(0.15)(Me₃SiO_(1/2))_(0.45)(SiO_(4/2))_(0.40)

(content of vinyl groups relative to content of all of the siliconatom-bonded organic groups: 8.3 mol %)

The following components were used as component (C).

Component (C-1): an organotrisiloxane represented by the formula:

HMe₂SiOPh₂SiOSiMe₂H

that had a viscosity of 4 mPa·sComponent (C-2): an organopolysiloxane represented by the average unitformula:

(HMe₂SiO_(1/2))_(0.40)(SiO_(4/2))_(0.60)

that had a viscosity of 20 mPa·s

The following component was used as component (D).

Component (D-1): solution of aplatinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (the solutioncontains 0.1% by mass of platinum)

The following component was used as component (E).

Component (E-1): 1-ethynylcyclohexanol

The following components were used as component (F).

Component (F-1): an adhesion-imparting agent prepared in SynthesisExample 7Component (F-2): an adhesion-imparting agent that had a viscosity of 30mPa·s and that was formed from a condensation reaction product of3-glycidoxypropyltrimethoxysilane and a methylvinylsiloxane oligomercapped at both molecular terminals with silanol groups

TABLE 1 Category Present invention Practical Practical PracticalPractical Practical Item Example 1 Example 2 Example 3 Example 4 Example5 Component (A-1) 15 — — — 15 Component (A-2) — 15 — — — Component (A-3)— — 15 — — Component (A-4) — — — 15 — Component (A-5) — — — — —Component (A-6) — — — — — Component (B-1) 57.68 59.66 59.05 58.82 —Component (B-2) — — — — 62.8 Component (B-3) — — — — — Component (B-4) —— — — — Component (C-1) 24.82 22.84 23.45 23.68 19.5 Component (C-2) — —— — — Component (D-1) 2.5 ppm 2.5 ppm 2.5 ppm 2.5 ppm 2.5 ppm Component(E-1) 0.03 0.03 0.03 0.03 0.03 Component (F-1) 2.3 2.3 2.3 2.3 2.5Component (F-2) — — — — — SiH/Vi 1.0 1.0 1.0 1.0 1.0 Viscosity (mPa · s)1300 2700 3900 3100 1400 Refractive index 1.523 1.524 1.525 1.526 1.509Tensile strength ◯ ◯ ◯ ◯ Δ Dispersibility of phosphor ◯ ◯ ◯ ◯ ◯ Crackresistance ◯ ◯ ◯ ◯ ◯ Category Present invention Comparative ExamplesPractical Practical Comparative Comparative Comparative Item Example 6Example 7 Example 1 Example 2 Example 3 Component (A-1) 44.32 — — — —Component (A-2) — 49.12 — — — Component (A-3) — — — — — Component (A-4)— — — — — Component (A-5) — — 15 15 — Component (A-6) — — — — 51.83Component (B-1) — — 59.43 — — Component (B-2) — — — 64.6 — Component(B-3) 8.64 8.64 — — 8.64 Component (B-4) 30.24 30.24 — — 30.24 Component(C-1) — — 23.07 17.7 — Component (C-2) 11 15.8 — — 8.29 Component (D-1)5 ppm 5 ppm 2.5 ppm 2.5 ppm 5 ppm Component (E-1) 0.03 0.03 0.03 0.030.03 Component (F-1) — — 2.3 2.5 — Component (F-2) 0.5 0.5 — — 0.5SiH/Vi 1.2 1.2 1.0 1.0 1.2 Viscosity (mPa · s) 400 1200 1900 2100 2000Refractive index 1.439 1.442 1.535 1.520 1.436 Tensile strength Δ Δ Δ XX Dispersibility of phosphor ◯ ◯ X Δ ◯ Crack resistance ◯ Δ ◯ ◯ X

As is clear from the results in Table 1, it was found that the curablesilicone compositions prepared in Practical Examples 1 to 7 exhibitedsuperior dispersibility of phosphor and superior balance of strength andgas barrier properties compared to those of the curable siliconecompositions prepared in Comparative Examples 1 to 3.

INDUSTRIAL APPLICABILITY

The curable silicone composition of the present invention exhibitsexcellent dispersibility of phosphor and forms a cured product havinghigh strength and gas barrier properties when the curable siliconecomposition is cured. Therefore, the curable silicone composition of thepresent invention is suitable as sealing agents, protective coatingagents, and the like of optical semiconductor elements in opticalsemiconductor devices, such as light emitting diodes (LEDs) and thelike.

REFERENCE NUMERALS

-   1 Optical semiconductor element-   2 Lead frame-   3 Lead frame-   4 Bonding wire-   5 Frame material-   6 Cured product of curable silicone composition

1. A curable silicone composition comprising: (A) an organopolysiloxanerepresented by the average unit formula:(R¹ ₃SiO_(1/2))_(a)(R² ₂SiO_(2/2))_(b)(R³SiO_(3/2))_(c) in the formula,R¹ are the same or different, and are alkyl groups having from 1 to 12carbon atoms, alkenyl groups having from 2 to 12 carbon atoms, arylgroups having from 6 to 20 carbon atoms, or aralkyl groups having from 7to 20 carbon atoms; R² are the same or different, and are alkyl groupshaving from 1 to 12 carbon atoms or alkenyl groups having from 2 to 12carbon atoms R³ is an alkyl group having from 1 to 12 carbon atoms, arylgroup having from 6 to 20 carbon atoms, or an aralkyl group having from7 to 20 carbon atoms, provided that, in a molecule, at least 0.5 mol %of a total content of the groups represented by R¹, R², and R³ are thealkenyl groups, at least one of the group represented by R³ is the arylgroup or the aralkyl group; and a, b, and c are numbers satisfying:0.01≦a≦0.5, 0.4≦b≦0.8, 0.01≦c≦0.5, and a+b+c=1; (B) from 20 to 1,000parts by mass, relative to 100 parts by mass of component (A), of anorganopolysiloxane represented by the average unit formula:(R⁴ ₃SiO_(1/2))_(d)(R⁴ ₂SiO_(2/2))_(e)(R⁴SiO_(3/2))_(f)(SiO_(4/2))_(g)in the formula, R⁴ are the same or different, and are alkyl groupshaving from 1 to 12 carbon atoms, alkenyl groups having from 2 to 12carbon atoms, aryl groups having from 6 to 20 carbon atoms, or aralkylgroups having from 7 to 20 carbon atoms, provided that, in a molecule,at least 0.5 mol % of the total content of the groups represented by R⁴are the alkenyl groups; and d, e, f, and g are numbers satisfying:0.01≦d≦0.5, 0≦e≦0.9, 0≦f≦0.9, 0≦g≦0.9, and d+e+f+g=1; however, if f is anumber satisfying: 0≦f≦0.5, g is a number satisfying: 0<g≦0.9; (C) anorganopolysiloxane having at least two silicon atom-bonded hydrogenatoms in a molecule, in an amount such that a content of the siliconatom-bonded hydrogen atoms contained in this component is from 0.1 to 10mol relative to 1 mol of the total content of the alkenyl groupscontained in components (A) and (B); and (D) a hydrosilylation reactioncatalyst, in an amount that accelerates curing of the composition. 2.The curable silicone composition according to claim 1, wherein component(A) is an organopolysiloxane in which R² of the average unit formula arethe same or different alkyl groups having from 1 to 12 carbon atoms. 3.The curable silicone composition according to claim 1, furthercomprising (E) a hydrosilylation reaction inhibitor, in an amount offrom 0.01 to 3 parts by mass per 100 parts by mass of the total amountof components (A) to (C).
 4. The curable silicone composition accordingto claim 1, further comprising (F) an adhesion-imparting agent, in anamount of from 0.1 to 5 parts by mass per 100 parts by mass of the totalamount of components (A) to (C).
 5. The curable silicone compositionaccording to claim 1, further comprising (G) a phosphor, in an amount offrom 0.1 to 70% by mass relative to the total amount of components (A)to (C).
 6. A cured product produced by curing the curable siliconecomposition according to claim
 1. 7. An optical semiconductor devicecomprising an optical semiconductor element sealed or coated with acured product of the curable silicone composition according to claim 1.8. The curable silicone composition according to 2, further comprising(G) a phosphor, in an amount of from 0.1 to 70% by mass relative to thetotal amount of components (A) to (C).
 9. A cured product produced bycuring the curable silicone composition according to claim
 5. 10. Anoptical semiconductor device comprising an optical semiconductor elementsealed or coated with a cured product of the curable siliconecomposition according to claim 5.